Analog Devices Inc./Maxim Integrated MAX6855UK35D2+T

Overview

The MAX6855UK35D2+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 3.5V reset threshold (±2.5%), and 40ms minimum reset timeout period. It provides active-high push-pull RESET output, manual reset input (MR), and operates across -40°C to +85°C for reliable power-up/brownout monitoring in battery-critical systems.

For engineers reviewing the MAX6855UK35D2+T datasheet, MAX6855UK35D2+T pinout, MAX6855UK35D2+T application, or MAX6855UK35D2+T equivalent, this device serves as a low-power voltage monitor with deterministic reset timing, MR-initiated recovery, and guaranteed RESET validity down to VCC = +1.1V - critical for portable medical and handheld electronics design validation.

Technical Context

This supervisory IC integrates voltage monitoring, manual reset assertion, and precise reset timing logic in a single BiCMOS die. Its internal 10kΩ MR pullup, glitch-immune MR input (200ns rejection), and VCC-to-RESET delay of 40µs ensure robust operation during noisy supply transients.

The active-high push-pull RESET output drives directly to VCC with VOH ≥ 0.8×VCC at ISOURCE = 500µA and VOL ≤ 0.3V at ISINK = 1.2mA (VCC ≥ 2.38V), eliminating external level-shifting components while maintaining compatibility with 1.8V–5.5V µP reset inputs.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount. Compact 2.9mm × 1.6mm footprint ideal for space-constrained portable designs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar microprocessor supervisory applications.

Compared with TPS3837K33DBVR and MAX6361KA33+T, the MAX6855UK35D2+T delivers 7× lower supply current, precise 3.5V threshold matching common LDO outputs, and integrated MR-making it optimal for next-gen portable medical devices requiring long service intervals and field-serviceable reset capability.

Availability

MAX6855UK35D2+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered instrumentation, and industrial wireless sensors requiring stable component supply across extended product lifecycles.

Supply support for MAX6855UK35D2+T includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Maxim Integrated (now part of Analog Devices) designs precision analog and mixed-signal ICs for demanding industrial, medical, and communications applications.

The MAX685x family targets ultra-low-power supervisory functions in battery-operated systems, emphasizing nanoscale current consumption, wide VCC range, and guaranteed reset behavior under marginal supply conditions.

FAQ

What is the exact reset threshold voltage for MAX6855UK35D2+T?

The MAX6855UK35D2+T has a factory-trimmed nominal reset threshold of 3.500V, with guaranteed tolerance of ±2.5% (3.413V to 3.588V) over -40°C to +85°C. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "35" corresponds to 3.500V. The MAX6855UK35D2+T uses this precise threshold to detect brownout on 3.3V or 3.6V supply rails.

Does MAX6855UK35D2+T include a watchdog timer function?

No, the MAX6855UK35D2+T does not include a watchdog timer. It belongs to the MAX6854/MAX6855/MAX6856 subgroup, which provides voltage monitoring and manual reset only. Watchdog functionality is exclusive to MAX6864–MAX6869 variants (e.g., MAX6864UK35D2S+T). The MAX6855UK35D2+T pinout lacks WDI, and its functional diagram confirms absence of watchdog circuitry.

What is the reset timeout period for MAX6855UK35D2+T?

The MAX6855UK35D2+T has a 40ms minimum reset timeout period, indicated by the "D2" suffix in its part number. Per Table 4 (Reset Timeout Periods), D2 specifies min/typ/max values of 40ms/60ms/80ms. This timeout ensures the microprocessor completes power stabilization and clock startup before release, and is fixed-not user-selectable-on this variant.

How does the MR input behave on MAX6855UK35D2+T?

The MR input on MAX6855UK35D2+T is active-low with an internal 10kΩ pullup to VCC. Driving MR low asserts RESET immediately, and RESET remains asserted for the full D2 timeout period (40ms min) after MR returns high. MR accepts CMOS logic levels and rejects glitches <200ns, making it suitable for direct connection to momentary switches or digital outputs without external debounce.

Is MAX6855UK35D2+T pin-compatible with other SOT23-5 supervisors?

Yes, the MAX6855UK35D2+T shares the same 5-pin SOT23-5 footprint and pinout (RESET, GND, MR, GND, VCC) as TPS3836/TPS3837/TPS3838 devices, as noted in the datasheet's Features section. However, electrical differences exist: MAX6855UK35D2+T uses active-high push-pull RESET, while TPS3837 offers open-drain. Direct replacement requires verifying RESET polarity and timing requirements in the target design.